This study aims at elucidating the mechanisms of bronchoconstriction in byssinosis and at obtaining information on the nature of the pharmacological agent(s) in textile dusts which cause bronchoconstriction. Our working hypothesis is that textile dusts contain a histamine releasing agent. We will prepare fractions of aqueous extracts on cotton bracts. Pharmacological activities of these fractions will be assessed in man after inhalation of aqueous aerosols using partial expiratory flow volume curves as the measure of response. In addition, we will determine the histamine releasing capacity of these fractions using pig lung tissue as the assay tissue. Biologically active fractions will be chemically characterized and techniques developed to isolate and, if possible, identify the active components which cause histamine release in vitro and bronchoconstriction in man in vivo. These results will allow a chemical determination of biological activity in textile dusts and may result in new and easily measurable standards of air quality in the industry.